Counterboring device



May 10, 1949. T. M. BONDHUS 7 2,469,543

COUNTER-BORING DEVICE Filed may 4, 1945 RmM-Bmdh s Pig-2 15 v Attorney Patented May 10, 1949 UNITED STATES PATENT OFFICE COUNTERBORING DEVICE Tom M. Bondhus, Monticello, Minn.

Application May 4, 1945, Serial No. 591,913

6 Claims.

My invention relates to an improvement in counter-boring device wherein it is desired to provide a simple and effective apparatus for producing a counter-bored aperture.

In producing a counter-bored aperture it has been common practice to mount a cutting blade on a suitable shank for the cutting operation. If this cutting tool projects from one side only of the shank considerable side strain is placed thereupon. On the other hand if the tool pro J'ects from opposite sides of the shank difficulty is experienced in maintaining the cutting tool centered relative to the shank and with the blade portions thereof at the same angle.

A feature of the present invention resides in the provision of a counter-boring tool which is of the double blade type and which obviates the difiiculties previously encountered with tools of this sort. The cutting tool is automatically centered and held in centered position and at the same time both of the cutting blades are maintained at the same angle and in directly opposed relationship.

A feature of the present invention resides in providing a double ended cutter tool having a pair of cutting blade surfaces on opposite ends thereof and in holding the blades at the same angle by means of a sleeve urged against the cutting edges. This sleeve is provided with an end which lies on a plane perpendicular to the axis of the counter-bore shank so that opposite sides of the sleeve will bear against the opposite ends of the cutting tool. As the cutting surface is angularly inclined and is generally cylindrical in shape this tool Will rotate in its aperture extending through the axis of the shank until both of the cutter blade surfaces are at the same angle.

A further feature of the present invention resides in cutting the cutter blade surfaces to provide shoulders engageable with the inner surface of the sleeve. By use of this construction, the cutter blade is held from longitudinal movement when mounted in place, thereby holding the blade properly centered relative to the shank.

A further feature of the present invention resides in the provision of a shank having a transverse opening therethrough and in providing opposed notches in the sides of the shank into which may extend projections on the end of the sleeve holding the center bar in place. These projections prevent the sleeve from rotating relative to the shank.

A further feature of the present invention resides in providing a cutter bar shank having a threaded-reduced diameter portion at one end 2 thereof and having opposed notches adjacent this reduced diameter portion. A sleeve encircles the reduced diameter portion of the shank and projects on this sleeve extending in the opposed notches to hold the sleeve from rotation. A nut or threaded collar holds the sleeve in place. As a result the cutter blade securing means is of no greater diameter than the body of the shank.

A further feature of the present invention resides in providing a shank with a reduced diameter threaded end portion and notches in the sides of the shank adjacent this reduced diameter portion; and in further providing an aperture through the shank having its axis at an acute angle to the bases of the notches. The notches specified are provided with parallel bases and the aperture through the shank extends at an acute angle to these parallel bases.

These and other objects and novel features of my invention will be more clearly and fully set forth in the following specification and claims.

In the drawings forming a part of my specification:

Figure 1 is a perspective view of my counterbore tool in exploded form.

Figure 2 is an elevational view partly in section showing the construction of my counterboring tool.

Figure 3 is a sectional view transversely through the shank at the axis of the cutter blade showing the cutter blade in full lines.

Figure 4 is an end view of the cutter blade.

The boring tool A comprises a cylindrical shank in having a reduced diameter shank portion ll concentric therewith at one end thereof. The reduced diameter portion ll is threaded as indicated at I2. A shoulder 13 is thus produced between the two different diameter portions l0 and II of the tool.

As best illustrated in Figure 3 of the drawings opposed notches Hand I5 are provided in the large diameter portion iii adjacent the small diameter portion II. The notches M and [5 are spaced apart a distance substantially equal to the diameter of the small diameter portion H, and the bases of the notches l4 and iii are parallel.

A cylindrical aperture I6 is provided through the shank I0 communicating with the notches l4 and [5. As again best illustrated in Figure 3 of the drawings the axis of the aperture [6 is at an acute angle to the parallel bases of the notches l4 and I5. In other words, the cutting tool does 66 not extend through the shank-with its axis'at right angles to the parallel bases of the notches I4 and IS.

A sleeve ll fits over the shank ll, being of an external diameter substantially equal to that of the shank I and having an internal diameter to snugly fit the shank portion ll. Projecting ears l9 and are provided on the sleeve I1 and are formed by cutting away the lower portion of the sleeve I! to produce the projections l9 and 20 having parallel inner faces. The inner faces of the projections i9 and 20 are spaced apart a distance just sufficient to enclose the parallel faces of the notches i4 and I5. In other words, in the absence of a cutter blade in the aperture IS, the projections l9 and 263 may enclose the notches l4 and i5 until the body of the sleeve ll engages the shoulder l3 on the shank.

An internally threaded nut or collar2l is designed to engage the threads l2 of the shank portion Ii so as to clamp the sleeve H in posi- -:tion. The collar 21 may be grooved asindicated at..22 forrotation by a screwv driver. or similar tool. The collar 2! is preferably of suflicient length to extend slightly beyond the threaded endof the shank portion H when the tool is in use.

The cutting tool is best illustrated in the eX- ploded view ofv Figure 1. This cutting tool2SHis ..provided with a cylindrical central portion 2% .and the upper surface of this .toolor bar is cut away at andit at an angle corresponding .to ..the anglebetween the cutter bar axis and the .bases of the notches M and it. As indicated in :Figure f :the drawings the surfaces 25 .and 125 .are :cutin such a manner that the :cylindrical portion .24 is of the same length and shape as ;the aperture 16, the cuttin of the cutter .bar providing shoulders 2'! and 29 designed to hold the cutter bar orblade from longitudinal move- ;ment. ,Each end of the blade .is also cut along a plane generallyparallel to ,the axis of the shank ..i l1,. these plane surfaces being indicated bythe numerals 3t and 3|.

:The surfaces 25 and 26 are upwardly inclined,

the angle of one end of theblade beingopposite k tothe angle'of the other end thereof. The high edgeu32 of one end of the blade occurs atthe juncture of the plane surfaces 25 and :30 .while xthehighedge 33 of the other end of the blade .occurs :at the juncture between .the plane surfaces 25 and 3!.

Inoperation the blade23 isinserted into ,the iapertureflt so that the ends of the -blade;,project an equal amount, at which time the shoulders2'l and 29 are flush with the bases of .the notches it and i5 respectively. At the time the sleeve H is appliedto -.the-shank H, the projectionssiil and 2t enclosing'the portion of the notches i4 and 15 most closely. adjacent the-.reduced diameter shank portion H. The projections -19v audit are of equallength and the undersurface of these projections in on a plane perpendicular to the axis of'the sleeve. As -a result the projections i9 and 2d engage-against the cutter blade '23 on'each side of the center of the blade.

'If the high'cdge 32 on-One'endof ithecutter blade is above the level of the high edge.i3.3 thereof, the projection it will engage the blade surface 25 ..before the projection .20 engages the surface .26. ,As aresult the cutter bar 2-3 will .be zsrotated about its axis until .the high edges (32 v.and;3 3 ofythetwo blade endsrare at the same .axial= distance. from the .butt endqof-the shank; H). Similarly if the blade. 23 is rotated soithat the notches it and W.

"from longitudinal movement.

high edge 33 is above the level of the edge 32 the projection 20 will engage in the plane surface 26 of the blade and will rotate the same about its axis until the edges 32 and 33 are at the same elevation or at the same axial distance from the butt end of the shank 50.

It will be noted that when the sleeve [1 is in place this sleeve is held from rotation by engagement of the projections 19 and 20 With the Furthermore the projections i9 and 2t engage outwardly of the shoulders 21 and 29 on the blade 23 thus holding the blade As a result when the nut or collar 2i is in place the cutter blade 23 is in proper relation with both its cutting edges 32 and 33 at the same distance from the end of the tool and the blade is held from angular or longitudinal movement.

In accordance with the patent statutes, I have described the principles of construction and operation of my counter-boring device, .,and 'while I have endeavored to set forththe best-embodiment thereof, I desire to have it understood that obvious changes may be made within the :scope of the following claims without departing .from the spirit of my invention.

I claim:

1. A counter-boring tool comprising a-shank, a pair of opposed notches in opposite sides of said shank, a sleeve engageable aboutsaidshank. and

includin projection means engageable into said opposed notches, an aperture throughsaid shank between said notches and .communicatingztherewith, a cutter blade in said aperture and :pro-

jecting at opposite sides of, the shank, said pro- ;jectionmeans engaging said cutter blade onop- :posite sides of .said shank.

.2. A counter-boring tool comprising a shank, a reduced diameter portion on said shank a pair of opposed, notches in said shank .adjacentsaid reduced diameter .portion, an aperture extending through said .shankcommunicating with said notches, a cuttin tool in said-aperture project- ..ing;from opposite sides of-said shank, a .collar encircling .said reduced ;diametei portionand-including projectionsengageable Withopposite sides of :said cuttingztool and .means for holding said icollar .in. place.

..3.3A counter-boring tool comprising a shank, a pair of notches; in opposite-sides of said shank,

an aperture extending transversely through said shank connecting said notches, acutterblade extendin through said .apertureand projecting from. opposite (sides of said shank, said cutter blade including an intermediate portion and-opposed cutting blade surfaces ontheoppositeends thereof, shoulders between:saidintermediate'portion. and saidcutting blade surfaces, .and means engaging saidshoulders to hold said blade from longitudinal movement.

4. A icountereboring .toolcomprising a :shank, a pair ofppposed notchesin said shank, ..an ap erturezthrough said shank. connecting .saidopposed notches, a-cutter blade. extendingsthrough said aperture, cutting .blade surfaces on :opposite ends of said blade, shoulders betweenisaid cutting blade surfaces and ..the remainder 50f said cutting blade asleeveencirclingsaid shank and includin projection :Ineans extending .into said notches and engageable ..outwardly :Of said shoulders :tohold. said cutting :blade from 21011- gitudinal movement.

5. 1A countereboring i tool comprising an elongated shank, a reduced a-diameter ,end portion thereupon, 1 opposed notches ;-in l-said ishank .ad-

jacent said reduced end portion, a sleeve encircling said reduced end portion, an aperture through said shank connecting said opposed notches, a sleeve encircling said reduced end portion and including projections engageable in said opposed notches, a cutter blade extending through said aperture, opposed cutting blade surfaces on opposite ends of said cutter blade, shoulders between said cutting bladesurfaces and the remainder of said cutter blade, said shoulders engaging inwardly of said projections to hold said cutter blade from longitudinal movement.

6. A counter-boring tool comprising a shank, a reduced diameter end thereupon, opposed notches in said shank adjacent said reduced diameter end, an aperture through said shank communicating with said notches, a sleeve engageable about the reduced diameter portion of said shank, a blade supported in said aperture projecting from opposite sides of said shank, opposed cutting edges on opposite ends of said blade, projections on said sleeve engageable in said notches and against said opposed cutting edges, and means for holding said collar means on said reduced diameter portion of said shank.

TOM M. BONDHUS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

